INTEGRATING ROCK PHYSICS AND SEISMIC INVERSION FOR QUANTITATIVE RESERVOIR ROCK PARAMETER PREDICTION

Seismic data to quantitatively predict the reservoir rock parameters is difficult because of the non-uniqueness of the inversion results and the inability to directly relate the petrophysical parameters to the elastic properties. The objective of this study is to integrate rock physics and seismic inversion for quantitative reservoir rock parameter prediction. It involves a combination of the well-log analysis method, the calibration of rock physics models (with the modified Hertz-Mindlin, critical porosity, and Gassmann fluid substitution models), pre-stack and post-stack inversion of the acoustic impedance. The method to determine the relationship between elastic properties and reservoir properties was cross-plot analysis and regression. The results revealed that there are significant negative relations between P-wave velocity and porosity, distinct lithology discrimination by Vp/VS and acoustic impedance and that fluid sensitivity is systematic as predicted by theory. To predict the porosity, the coefficients of determination and fluid saturation estimation were higher than 0.75 and 0.80, respectively, with a percentage error of prediction less than 10 per cent, showing increased strength and less interpretational uncertainty.